The present disclosure relates to an image forming apparatus including an static eliminating device eliminating a static charge remained on a surface of a photosensitive drum and a separating claw separating a recording sheet with a transferred toner from the photosensitive drum, and a light concentrating device arranged between the photosensitive drum and static eliminating device.
In a general manner of forming an image, a surface of a photosensitive drum is electrically charged to a predetermined electrical potential by a charging device and an electrostatic latent image according to image data is formed on the surface by photographic exposure. The electrostatic latent image is developed with a toner (a developer) by a development device, and then, transferred on a recording sheet by a transferring device. The toner remained on the surface of the photosensitive drum is removed by a cleaning device and a static charge remained on the photosensitive drum is eliminated by a static eliminating device. In the photosensitive drum, a cycle having such electrical charging, photographic exposure and static elimination is repeated in the image forming.
In the transferring device, voltage with an opposite polarity to the toner is applied onto an opposite face to a face having the transferred toner in the recording sheet and the toner is transferred onto the recording sheet from the photosensitive drum. At this time, the recording sheet may be electrically charged and electrostatically attracted to the photosensitive drum. Such a disposition is remarkably occurred particularly in a thin recording sheet. In response, there is an image forming apparatus including a separating claw coming into contact with the photosensitive drum in a counter direction to a rotating direction of the photosensitive drum. The separating claw forcedly separates a leading edge of the recording sheet from the photosensitive drum.
Further, the image forming apparatus may include a conveyance auxiliary member at a downstream side from the separating claw in a conveying direction of the recording sheet. The conveyance auxiliary member is configured to guide the recording sheet so as to prevent an unfixed toner from contacting with components and others in the periphery of a conveying path of the recording sheet due to flotation of recording sheet after the recording sheet is separated by the separating claw. In the conveying path of the recording sheet, it is necessary to provide a space with a certain degree of a height above a toner transferred face of the recording sheet.
Meanwhile, according to space saving, miniaturization of the photosensitive drum and acceleration of the image forming apparatus are progressed, and accordingly, a time from the static elimination of the photosensitive drum to the electrical charging in a next cycle is shortened. Therefore, it is necessary to consider an exposure memory of the photosensitive drum. The exposure memory is a phenomenon in which, between an exposed area and an unexposed area in the photosensitive drum after the static elimination, surface electrical potentials are different from each other, and then, the surface of photosensitive drum is electrically charged unevenly in the electrical charging in the next cycle. Due to this phenomenon, a defective image called as a ghost may be occurred. A problem of the exposure memory is feared particularly in an amorphous silicon photoreceptor. As a countermeasure to this problem, it is necessary to provide an interval between the static eliminating device and charging device as wider as possible and to secure a time sufficiently attenuating the surface electrical potential of the photosensitive drum before the electrical charging in the next cycle. Therefore, it is necessary to position the static eliminating device at an upstream side from the cleaning device in the rotating direction of the photosensitive drum.
However, the separating claw and conveyance auxiliary member must be positioned at the upstream side from the cleaning device in the rotating direction of the photosensitive drum. Therefore, if the interval between the static eliminating device and charging device is provided wider in order to solve the exposure memory, and moreover, the separating claw and conveyance auxiliary member are provided, it is necessary to arrange the static eliminating device, separating claw and conveyance auxiliary member between the transferring device and cleaning device. Further, between the transferring device and cleaning device, it is necessary to provide another space protecting the toner transferred face of the recording sheet. If the photosensitive drum is miniaturized, the space between the transferring device and cleaning device becomes narrower.